LED lighting devices are often tested under high voltages before leaving the factory. Such high-voltage testing is designed to detect voltage-resistant capabilities of the LED lighting devices under extreme conditions and to detect whether an electric shock would occur when touched by a human body.
Conventional testing methods include wrapping a metal heat-dissipation lamp cup and a lamp head with a layer of metal foil and then using electrical clamps to clamp two pieces of metal foil. A high voltage of about 1500V to 4000V can be applied to the two pieces of metal foil to detect eligibility of the LED lighting device.
However, LED light sources (often made by a chip) of LED lighting devices may be broken down to cause damages and big losses during such high-voltage testing. This may be because that a circuit for a small amount of leakage current can be formed between the lamp head, a power supply, and the LED light sources during the high-voltage testing. When this small amount of leakage current exceeds a tolerance limit of the LED light sources, these LED light sources may be broken down.